In 2015, in the area around Chicago, an outbreak of influenza began to sicken dogs. That virus was eventually determined to be different from the H3N8 typically seen in the US, instead being classified as H3N2, a virus previously causing illness in dogs in southern China and South Korea. At the time of this writing, dogs have been diagnosed with this strain of flu in 29 states.

What Is Influenza and What Are the Signs That a Cat May Have It?

Influenza is a respiratory illness caused by a virus that can cause fever, sore joints, coughing, and runny nose.

In dogs, it is usually a mild illness that resolves on its own within a week or two. However, some cases may become complicated and develop into pneumonia. This is most common in very young or old dogs or those with concurrent medical conditions.

Cats have been known to be infected with flu viruses in the past, but it hasn't been common or widespread. When they are affected, the illness is usually mild, but as is the case in dogs and humans, it is possible for it to develop into pneumonia and potentially cause death in certain individual cats.

Can Cats Get H3N2?

The H3N8 virus that was previously known to cause most of the influenza infections in dogs in the US was not transmissible to cats. However, when the Chicago outbreak of influenza in dogs was determined to be due to an H3N2 virus instead, scientists speculated that it may be able to infect cats based on its history of doing so in southern China and South Korea, where the virus originated.

In April 2016, a group of eight cats in a shelter in Indiana tested positive for H3N2. The cats had been showing signs of respiratory illness such as sneezing, runny nose, listlessness, and excessive salivation. Dogs in the same shelter also tested positive for H3N2, but they were housed in a separate area of the building from the cats. This highlights how contagious the H3N2 virus is.

As of this writing, all of the cats in the shelter have either recovered or are recovering from their flu infections. There were no fatalities due to influenza in this outbreak.

Diagnosis of H3N2 in Cats

H3N2 can be diagnosed in cats through a test called serology, which looks for the presence of the virus in a blood or mucus sample. Repeated serology tests to compare amounts of the virus present can verify that the infection is active.

The signs of influenza in cats can mimic those of many other illnesses, so it's important to get your cat to the veterinarian if you see any indications that she may be sick. Some signs to watch for include:

Listlessness

Sneezing

Coughing

Congestion

Decreased appetite

Treatment of Flu in Cats

The treatment of flu in cats is usually supportive in nature. Most cats will clear the infection on their own without treatment. Strict monitoring by the owner is required to ensure that the illness doesn't spread to the cat's lungs or cause her to stop eating. Sicker cats may need to be supported with intravenous fluids or other medications.

Prevention of Flu in Cats

You can minimize your cat's chances of being infected by the H3N2 flu virus by keeping her inside and avoiding grooming and kennel facilities when possible.

It's also important to know the signs of influenza in cats so that if you see anything that could indicate your cat has been infected, you can make an appointment with your veterinarian right away.

It's possible for your cat to be infected by a dog, so it's important to understand how flu affects your canine family members, as well. You can learn more about that here: "Canine Influenza."

Disclaimer: This website is not intended to replace professional consultation, diagnosis, or treatment by a licensed veterinarian. If you require any veterinary related advice, contact your veterinarian promptly. Information at CatHealth.com is exclusively of a general reference nature. Do not disregard veterinary advice or delay treatment as a result of accessing information at this site. Just Answer is an external service not affiliated with CatHealth.com.